Lighting system

ABSTRACT

A lighting system includes a lighting unit comprising at least one lighting device, a sensing unit configured to measure at least one of atmospheric temperature and humidity, a controlling unit configured to compare the at least one of the temperature and the humidity measured by the sensor unit with set values and determine a color temperature of the lighting unit as a result of the comparison, and a driving unit configured to drive to the lighting unit to have the determined color temperature.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.14/698,575 filed Apr. 28, 2015, which claims the priority to KoreanPatent Application No. 10-2014-0124151 filed on Sep. 18, 2014, with theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference in their entirety.

BACKGROUND

The present inventive concept relates to alight system includingsemiconductor light emitting devices.

A semiconductor light emitting device such as a light emitting diode(LED), a device containing a light emitting material therein to emitlight, may convert energy generated due to recombination of electronsand electron holes into light to be emitted therefrom. Such a lightemitting diode (LED), having many positive attributes, such as arelatively long lifespan, low power consumption, a rapid response rate,environmentally friendly characteristics, and the like, as compared witha light source according to the related art, is currently in widespreaduse as a lighting element, a display device and alight source, and thedevelopment thereof has been accelerated.

With the recent enlargement of the scope of application of LEDs, the useof LEDs has been extended to light sources in high current/high outputapplication fields. As LEDs are required in high current/high outputapplication fields as described above, research into improvements inlight emitting efficiency has been continuously conducted in thetechnical field.

SUMMARY

An exemplary embodiment of the present inventive concept may provide alight system including a semiconductor light emitting device havingimproved light emitting efficiency and light output by increasinginjection efficiency of holes through the disposition of ahole-diffusion layer.

According to an exemplary embodiment of the present inventive concept, Alighting system may include a lighting unit comprising at least onelighting device, a sensing unit configured to measure at least one ofatmospheric temperature and humidity, a controlling unit configured tocompare the at least one of the temperature and the humidity measured bythe sensor unit with set values and determine a color temperature of thelighting unit as a result of the comparison, and a driving unitconfigured to drive to the lighting unit to have the determined colortemperature.

The at least the lighting device includes at least one semiconductorlight emitting device.

the semiconductor light emitting device may include a first conductivitytype semiconductor layer, an active layer disposed on the firstconductivity type semiconductor layer, an electron-blocking layerdisposed on the active layer, a second conductivity type semiconductorlayer disposed on the electron-blocking layer, and a hole-diffusionlayer disposed between the electron-blocking layer and the secondconductivity type semiconductor layer. The hole-diffusion layer mayinclude three layers having different energy band gaps and differentresistance levels and at least one of the three layers contains Al, acomposition of the Al being lower in the at least one layer than in theelectron-blocking layer.

The at least one lighting device may include a first lighting deviceconfigured to emit a first white light having a first color temperature,and a second lighting device configured to emit a second white lighthaving a second color temperature.

The first color temperature may be equal to or higher than 6000K and thesecond color temperature may be equal or lower than 4000K.

The controller unit may be configured to control the driving unit todrive the first lighting device and the second lighting device togenerate white light having the determined color temperature.

The three layers of the hole-diffusion layer may include a first layerformed of In_(x1)Ga_(1−x1)N (0<x1<1), a second layer formed of GaN, anda third layer formed of Al_(x2)Ga_(1−x2)N (0<x2<1) that are sequentiallydisposed on the electron-blocking layer.

The hole-diffusion layer may further include an additional layer ofIn_(x3)Ga_(1−x3)N (0<x3<1) interposed between the second and thirdlayers.

The three layers of the hole-diffusion layer may include a first layerformed of GaN, a second layer formed of In_(x1)Ga_(1−x1)N (0<x1<1), anda third layer formed of Al_(x2)Ga_(1−x2)N (0<x2<1), sequentiallydisposed on the electron-blocking layer.

The three layers of the hole-diffusion layer may include a first layerformed of GaN, a second layer formed of Al_(x2)Ga_(1−x2)N (0<x2<1), anda third layer formed of In_(x1)Ga_(1−x1)N (0<x1<1), sequentiallydisposed on the electron-blocking layer.

Thicknesses of the respective layers forming the hole-diffusion layermay be within a range of 5 nm to 30 nm.

A lighting system may include a lighting unit comprising at least onelighting device, a sensing unit configured to measure at least one ofatmospheric temperature and humidity, a controlling unit configured tocompare the at least one of the temperature and the humidity measured bythe sensor unit with set values and determine a color temperature of thelighting unit as a result of the comparison, and a driving unitconfigured to drive to the lighting unit to have the determined colortemperature. The lighting device may include at least semiconductorlight emitting device comprising an n-type semiconductor layer and ap-type semiconductor layer, an active layer disposed between the n-typesemiconductor layer and the p-type semiconductor layer, anelectron-blocking layer disposed between the active layer and the p-typesemiconductor layer, a diffusion barrier layer disposed between theactive layer and the electron-blocking layer, and a hole-diffusion layerdisposed between the electron-blocking layer and the p-typesemiconductor layer. The hole-diffusion layer may include three layershaving different compositions and different dopant-doping concentrationsand at least one of the three layers contains Al, a composition of theAl being lower in the at least one layer than in the electron-blockinglayer.

The diffusion barrier layer may include a semiconductor material formedof Al_(c)In_(d)Ga_(1−c−d)N (0≦c<1, 0≦d<1, 0≦c+d≦1), and the diffusionbarrier layer has an energy band gap greater than an energy band gap ofthe active layer and an energy band gap of the p-type semiconductorlayer.

A lighting system may include a lighting unit comprising at least onelighting device, a sensing unit configured to measure at least one ofatmospheric temperature and humidity, a controlling unit configured tocompare the at least one of the temperature and the humidity measured bythe sensor unit with set values and determine a color temperature of thelighting unit as a result of the comparison, and a driving unitconfigured to drive to the lighting unit to have the determined colortemperature. the lighting device may comprise at least semiconductorlight emitting device comprising a first conductivity type semiconductorlayer, an active layer disposed on the first conductivity typesemiconductor layer, an electron-blocking layer disposed on the activelayer, a second conductivity type semiconductor layer disposed on theelectron-blocking layer, and a hole-diffusion layer disposed between theelectron-blocking layer and the second conductivity type semiconductorlayer. The hole-diffusion layer may include three layers havingdifferent energy band gaps and at least one of the three layers containsAl, a composition of the Al in any layer of the hole-diffusion layerbeing lower than in the electron-blocking layer.

Among the three layers of the hole-diffusion layer, a layer having thelargest energy band gap may have the largest thickness and a layerhaving the smallest energy band gap may have the smallest thickness.

The semiconductor light emitting device may further include a diffusionbarrier layer, containing a semiconductor material formed ofAl_(c)In_(d)Ga_(1−c−d)N (0≦c<1, 0≦d<1, 0≦c+d≦1), disposed between theactive layer and the electron-blocking layer.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features and other advantages of thepresent inventive concept will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to an exemplary embodimentof the present inventive concept;

FIG. 2 is a diagram illustrating energy band gaps in a partial laminatestructure of the semiconductor light emitting device according to anexemplary embodiment illustrated in FIG. 1;

FIG. 3 is a graph illustrating energy band gaps and lattice constants ofa nitride semiconductor;

FIG. 4 is a graph illustrating characteristics of the semiconductorlight emitting device according to an exemplary embodiment of thepresent inventive concept through comparative experimentation;

FIGS. 5A through 5G are diagrams each illustrating energy band gaps in apartial laminate structure of a semiconductor light emitting deviceaccording to exemplary embodiments modified from FIG. 1;

FIGS. 6 through 9 are cross-sectional views illustrating various formsof semiconductor light emitting devices employable in other exemplaryembodiments of the present inventive concept;

FIGS. 10 and 11 are cross-sectional views of light emitting devicepackages illustrating examples in which the semiconductor light emittingdevice according to an exemplary embodiment of the present inventiveconcept is applied to the packages;

FIG. 12 is the CIE 1931 coordinate system illustrating a wavelengthconversion material employable in an exemplary embodiment of the presentinventive concept;

FIGS. 13 and 14 each illustrate a light source module employable in alighting device according to an exemplary embodiment of the presentinventive concept;

FIGS. 15 and 16 are cross-sectional views each illustrating an examplein which the semiconductor light emitting device according to anexemplary embodiment of the present inventive concept is applied to abacklight unit;

FIGS. 17 through 19 are exploded perspective views of lighting devices,each illustrating an example in which the semiconductor light emittingdevice according to an exemplary embodiment of the present inventiveconcept is applied to the lighting device;

FIG. 20 is a block diagram schematically illustrating a lighting systemaccording to an exemplary embodiment of the present inventive concept;

FIG. 21 is a block diagram schematically illustrating a detailedconfiguration of a lighting unit in the lighting system shown in FIG.20;

FIG. 22 is a flowchart illustrating a method of controlling the lightingsystem shown in FIG. 20;

FIG. 23 is an exemplary view schematically illustrating the use of thelighting system shown in FIG. 20; and

FIG. 24 is a cross-sectional view of a head lamp, illustrating anexample in which the semiconductor light emitting device according to anexemplary embodiment of the present inventive concept is applied to thehead lamp.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present inventive concept willbe described in detail with reference to the accompanying drawings.

The disclosure may, however, be exemplified in many different forms andshould not be construed as being limited to the specific embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

In the drawings, the shapes and dimensions of elements may beexaggerated for clarity, and the same reference numerals will be usedthroughout to designate the same or like elements.

FIG. 1 is a cross-sectional view schematically illustrating asemiconductor light emitting device 100 according to an exemplaryembodiment of the present inventive concept. FIG. 2 is a diagramillustrating energy band gaps in a partial laminate structure of thesemiconductor light emitting device 100 according to an exemplaryembodiment illustrated in FIG. 1.

Referring to FIG. 1, the semiconductor light emitting device 100according to the exemplary embodiment may include a substrate 10, afirst conductivity type semiconductor layer 21 and a second conductivitytype semiconductor layer 22 formed on the substrate 10, an active layer23 disposed between the first and second conductivity type semiconductorlayers 21 and 22, and an electron-blocking layer 24 disposed between theactive layer 23 and the second conductivity type semiconductor layer 22.In addition, the semiconductor light emitting device 100 according tothe exemplary embodiment may further include a hole-diffusion layer 25between the electron-blocking layer 24 and the second conductivity typesemiconductor layer 22. In addition, first and second electrodes 21 aand 22 a may be disposed on the first and second conductivity typesemiconductor layers 21 and 22 to be electrically connected thereto,respectively.

Meanwhile, the first conductivity type semiconductor layer 21 may be ann-type semiconductor layer doped with an n-type dopant, and the secondconductivity type semiconductor layer 22 may be a p-type semiconductorlayer doped with a p-type dopant.

The substrate 10 may be provided as a semiconductor growth substrate andmay be formed of an insulating or a conductive semiconductor materialsuch as sapphire, silicon (Si), silicon carbide (SiC), MgAl₂O₄, MgO,LiAlO₂, LiGaO₂, or GaN. In this case, the substrate 10 may be preferablyformed of sapphire having electrical insulation properties. Sapphire isa crystal having Hexa-Rhombo R3c symmetry, of which lattice constants inc-axis and a-axis directions are 13.001 Å and 4.758 Å, respectively. Asapphire crystal has a C-plane (0001), an A-plane (11-20), an R-plane(1-102), and the like. In this case, since a nitride semiconductor filmcan be relatively easily formed on the C-plane of the sapphire crystaland the C-plane is stable at high temperature, it is commonly used as agrowth substrate for a nitride semiconductor film.

In addition, another material suitable for use in the substrate 10 maybe, for example, a silicon (Si) substrate. The mass producibility may beimproved by using the silicon (Si) substrate which is relativelyinexpensive and suitable for being formed to have a large diameter. Inthe case of using the silicon (Si) substrate, after forming a bufferlayer formed of a substance such as AlGaN on the substrate 10, a nitridesemiconductor having a desired structure may grown on the buffer layer.

Meanwhile, the substrate 10 may be removed after a semiconductorlaminate including the first and second conductivity type semiconductorlayers 21 and 22 and the active layer 23 interposed therebetween hasbeen grown. For example, the sapphire substrate may be removed using alaser lift-off (LLO) process of irradiating a laser beam onto aninterface between the sapphire substrate and the semiconductor laminate,and a Si substrate and a SiC substrate may be removed by a method suchas polishing, etching or the like.

In the exemplary embodiment, a buffer layer 12 may be interposed betweenthe substrate 10 and the first conductivity type semiconductor layer 21.In general, when a semiconductor laminate is grown on the substrate 10,for example, when a GaN film serving as the first conductivity typesemiconductor layer 21 is grown on a heterogeneous substrate, latticedefects such as dislocations may be caused due to a difference inlattice constants between the substrate 10 and the GaN film. Inaddition, the substrate 10 may be warped due to a difference incoefficients of thermal expansion, such that cracks may occur in thesemiconductor laminate. In order to control the warpage and the defects,after forming the buffer layer 12 on the substrate 10, a semiconductorlaminate having a desired structure, for example, the first conductivitytype semiconductor layer 21 formed of a nitride semiconductor may grownon the buffer layer 12.

The buffer layer 12 may be formed of a material, for example,Al_(m)In_(n)Ga_(1−m−n)N (0≦m≦1, 0≦n≦1), in particular, GaN, AlN, orAlGaN. For example, the buffer layer 12 may be an undoped GaN layerundoped with a dopant and be formed to have a predetermined thickness.

It goes without saying that the buffer layer 12 is not limited thereto.Thus, any material may be used, as long as it has a structure allowingfor improvements in crystallinity of the semiconductor laminate. Amaterial such as ZrB₂, HfB₂, ZrN, HfN, TiN, ZnO or the like may also beused. In addition, a combination of a plurality of layers or a layerformed by gradually changing a composition may also be used for thematerial of the buffer layer 12.

The first and second conductivity type semiconductor layers 21 and 22may be formed of a nitride semiconductor, for example, a material havinga composition of Al_(p)In_(q)Ga_(1−p−q)N (0≦p<1, 0≦q<1, 0≦p+q<1). In theexemplary embodiment, the first and second conductivity typesemiconductor layers 21 and 22 may be formed of GaN doped with an n-typedopant and GaN doped with a p-type dopant, respectively.

The active layer 23 may emit light having a predetermined wavelength dueto recombination of electrons and holes. The active layer 23 may bedisposed between the first and second conductivity type semiconductorlayers 21 and 22 and have a multiple quantum well (MQW) structure inwhich quantum well and quantum barrier layers are alternately stacked.For example, in the case of a nitride semiconductor, the active layer 23may have a structure in which quantum well layers formed ofIn_(y1)Ga_(1−y1)N (0<y1<1) and quantum barrier layers formed ofAl_(x2)In_(y2)Ga_(1−x2−y2)N (0≦x2<1, 0≦y2<y1, 0≦x2+y2<1) are alternatelystacked.

Depending on exemplary embodiments, the active layer 23 may have asingle-quantum well (SQW) structure including a single quantum welllayer.

Meanwhile, electrons having been moved from the first conductivity typesemiconductor layer 21 to the active layer 23 may pass through theactive layer 23 and overflow to the second conductivity typesemiconductor layer 22. The electrons overflowing to the secondconductivity type semiconductor layer 22 may be recombined with holes ina region except for the active layer 23, that is, in a non-lightemitting region. The recombination may correspond to a nonradiativerecombination, thereby degrading light emission efficiency of asemiconductor light emitting device. In order to reduce the nonradiativerecombination, the electron-blocking layer 24 may be provided betweenthe active layer 23 and the second conductivity type semiconductor layer22.

Referring to FIG. 2 together with FIG. 1, the electron-blocking layer 24may have an energy band gap greater than an energy band gap of the lastquantum barrier layer of the active layer 23 in order to block theelectrons overflowing from the active layer 23 to the p-typesemiconductor layer (for example: the second conductivity typesemiconductor layer 22). For example, the electron-blocking layer 24 maybe formed of Al_(r)Ga_(1−r)N (0<r≦1). In the exemplary embodiment, r inthe Al composition of the electron-blocking layer 24 may be reduced in adirection away from the active layer 23. Thus, an energy band gap (Eg)of the electron-blocking layer 24 may be reduced in a direction awayfrom the active layer 23. FIG. 2 illustrates a case in which an energyband gap (Eg) in an upper portion of the electron-blocking layer 24adjacent to the hole-diffusion layer 25 is greater than an energy bandgap (Eg) of the second conductivity type semiconductor layer 22, but isnot limited thereto.

Depending on exemplary embodiments, the energy band gap (Eg) in theupper portion of the electron-blocking layer 24 may be identical to theenergy band gap (Eg) of the second conductivity type semiconductor layer22.

Depending on exemplary embodiments, the electron-blocking layer 24 maybe formed of Al_(r)Ga_(1−r)N (0<r≦1) in which r in the Al composition isnot varied in a direction away from the active layer 23. That is, theelectron-blocking layer 24 may be an AlGaN layer having a uniform Alcomposition.

Meanwhile, since the electron-blocking layer 24 may block the electronsoverflowing from the active layer 23 to the second conductivity typesemiconductor layer 22 but may also hinder the movement of holes movingfrom the second conductivity type semiconductor layer 22 to the activelayer 23, the electron-blocking layer 24 may be doped with a p-typedopant. The p-type dopant may be, for example, Mg, but is not limitedthereto.

When a p-type GaN material is formed using a metal-organic chemicalvapor deposition (MOCVD) process in the technical field, Mg atoms usedas a doping material are not completely substituted with the site of Gaand may be combined with pyrolyzed hydrogen from NH₃ injected as anitrogen source to form an Mg—H complex, thereby causing difficulties inthe activation of Mg. Thus, even in the case that an Mg concentration ofa p-type GaN layer actually doped with Mg is approximately 10¹⁹ to10²¹/cm³, the concentration of holes, carriers after heat treatments fordopant activation, may be approximately 5×10¹⁷/cm³, considerably low ascompared to the concentration of electrons, carriers of an n-type GaNlayer doped with Si, on a level of 1×10¹⁹/cm³. Due to the excessivelydoped Mg atoms or Mg—H complex, a non-uniform hole current may be causedwithin the p-type semiconductor layer and accordingly, the efficiency ofinjecting holes into the active layer may be degraded. Therefore, lightemission efficiency of the semiconductor light emitting device may bedecreased.

In order to improve the light emission efficiency of the semiconductorlight emitting device, it may be necessary to improve the non-uniformhole current in the interior of the p-type semiconductor layer and toincrease the efficiency of injecting holes into the active layer. Tothis end, the semiconductor light emitting device according to anexemplary embodiment of the present inventive concept may furtherinclude the hole-diffusion layer 25 able to disperse the non-uniformhole current.

Referring to FIG. 2 together with FIG. 1, the hole-diffusion layer 25disposed between the electron-blocking layer 24 and the secondconductivity type semiconductor layer 22 may have three layers 25 a, 25b and 25 c having different energy band gaps Eg and different specificresistance levels. The three layers 25 a, 25 b and 25 c of thehole-diffusion layer 25 may be formed of different nitride semiconductorcompounds. In the exemplary embodiment, the hole-diffusion layer 25 mayinclude a first layer 25 a formed of In_(x1)Ga_(1−x1)N (0<x1<1), asecond layer 25 b formed of GaN and a third layer 25 c formed ofAl_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposed on theelectron-blocking layer 24. Thus, an energy band gap Eg of the firstlayer 25 a may be the smallest and an energy band gap Eg of the thirdlayer 25 c may be the largest.

Meanwhile, in the exemplary embodiment, x1 in the In composition of thefirst layer 25 a may be less than y1 in the In composition of a quantumwell layer 23 a of the active layer 23. However, the present inventiveconcept is not limited thereto and depending on exemplary embodiments,x1 in the In composition of the first layer 25 a may be greater than y1in the In composition of the quantum well layer 23 a of the active layer23. In the exemplary embodiment, x2 in the Al composition of the thirdlayer 25 c may be less than r in the Al composition of theelectron-blocking layer 24.

Since the first layer 25 a, the second layer 25 b, and the third layer25 c are formed of different compositional compounds as described above,even in the case that they are undoped with a dopant or are doped with adopant at the same concentration, they may have different specificresistance levels. Meanwhile, the first layer 25 a, the second layer 25b, and the third layer 25 c are doped with a p-type dopant at differentconcentrations, whereby they may have different specific resistancelevels. At least one layer from among the first layer 25 a, the secondlayer 25 b, and the third layer 25 c may not contain an intentionallydoped dopant. For example, in the exemplary embodiment, the third layer25 c may be a GaN semiconductor layer containing Al without anintentionally doped dopant.

Thicknesses of the first layer 25 a, the second layer 25 b, and thethird layer 25 c forming the hole-diffusion layer 25 may beappropriately determined within a range of 5 nm to 30 nm inconsideration of electrical resistance levels or crystalline defectscaused by lattice mismatches in the respective layers. In the exemplaryembodiment, the thickness of the first layer 25 a having the smallestenergy band gap Eg is the smallest, while the thickness of the thirdlayer 25 c having the largest energy band gap Eg is the greatest.

Meanwhile, the first conductivity type semiconductor layer 21, thesecond conductivity type semiconductor layer 22, the active layer 23,the electron-blocking layer 24, and the hole-diffusion layer 25 may begrown using a process well known in the technical field, such as metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE),hydride vapor phase epitaxy (HVPE), or the like.

FIG. 3 is a graph illustrating energy band gaps and lattice constants ofrespective compounds. FIG. 3 is a graph showing relationships betweenenergy band gaps Eg and respective compositions of a nitridesemiconductor (a compositional ratio of Al, In and Ga).

Referring to FIG. 3, AlN has the smallest lattice constant and thelargest energy band gap Eg, while InN has the largest lattice constantand the smallest energy band gap Eg. A composition of Al, Ga or In maybe appropriately adjusted within a triangular region formed by GaN, AlNand InN, whereby a semiconductor layer having an energy band gap beingwithin a range from approximately 2 eV to approximately 6 eV may beformed.

FIG. 4 is a graph illustrating characteristics of the semiconductorlight emitting device according to an exemplary embodiment of thepresent inventive concept through comparative experimentation.Specifically, FIG. 4 is a graph in which internal quantum efficiency(IQE) of the semiconductor light emitting device 100 according to theexemplary embodiment described with reference to FIGS. 1 and 2 iscompared with that of a comparative example.

The comparative example is a semiconductor light emitting device thatdoes not include the hole-diffusion layer 25, unlike the semiconductorlight emitting device 100 according to the exemplary embodiment. Thatis, a graph indicated as the comparative example in FIG. 4 refers tointernal quantum efficiency (IQE) of a semiconductor light emittingdevice in which the second conductivity type semiconductor layer 22 isdisposed directly on the electron-blocking layer 24.

Referring to FIG. 4, it could be confirmed that a phenomenon of areduction of internal quantum efficiency (IQE) according to an increasein current was smaller in the exemplary embodiment than in thecomparative example. That is, it could be confirmed that in the case ofthe inventive example, a droop phenomenon of internal quantum efficiency(IQE) was improved toward a high current region, as compared to the caseof the comparative example. In other words, according to the exemplaryembodiment, a semiconductor light emitting device having improved lightemission efficiency in a high current region may be obtained. Such aresult may be obtained by forming the hole-diffusion layer 25 includingat least three or more layers having different specific resistancelevels to effectively disperse holes in a transverse direction, therebyallowing for improvements in injection efficiency of the holes injectedinto the active layer 23. In addition, it is due to the fact that thehole-diffusion layer 25 having a structure in which multiple layershaving different energy band gaps are present may be disposed to beadjacent to the electron-blocking layer 24, whereby a hole barrier in avalence band may be mitigated and accordingly, the efficiency ofinjecting holes into the active layer 23 may be improved.

Moreover, although not illustrated, light output characteristics of thesemiconductor light emitting device 100 according to the exemplaryembodiment were also improved as compared the case of the comparativeexample by 3%.

Hereinafter, remaining configurations of the semiconductor lightemitting device 100 according the exemplary embodiment will be describedwith reference to FIG. 1, again.

The semiconductor light emitting device 100 may include the firstelectrode 21 a electrically connected to the first conductivity typesemiconductor layer 21 and the second electrode 22 a electricallyconnected to the second conductivity type semiconductor layer 22. Thefirst and second electrodes 21 a and 22 a may be provided as elementsfor applying driving power to the semiconductor light emitting device100. The first and second electrodes 21 a and 22 a may be a materialselected from Ag, Al, Ni, Cr, Pd, Cu, Pt, Sn, W, Au, Rh, Ir, Ru, Mg, Znand the like. The first and second electrodes 21 a and 22 a may beformed by a process such as a deposition process, a sputtering process,a plating process or the like. In addition, the first and secondelectrodes 21 a and 22 a may respectively have a structure of two ormore layers formed of materials such as Ni/Ag, Zn/Ag, Ni/Al, Zn/Al,Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al or Ni/Ag/Pt. Since the materialof the first and second electrodes 21 a and 22 a is not limited to thematerials described above, a material capable of being in ohmic contactor electrical contact with the first and second conductivity typesemiconductor layers 21 and 22 among conductive or reflective materialsmay be employed.

An ohmic electrode layer 22 b may be formed between the secondconductivity type semiconductor layer 22 and the second electrode 22 a.The ohmic electrode layer 22 b may be formed of a material exhibitingelectrical ohmic characteristics with respect to the second conductivitytype semiconductor layer 22. Meanwhile, in the case of a light emittingdevice having a structure in which light having been generated from theactive layer 23 passes through the second conductivity typesemiconductor layer 22 to be emitted outwardly, the ohmic electrodelayer 22 b may be formed of a transparent conductive material having ahigh degree of light transmittance as well as relatively excellent ohmiccharacteristics, such as ITO, CIO, ZnO, graphene or the like, amongtransparent electrode materials, but is not limited thereto.

In addition, in the case of a light emitting device having a structurein which light having been generated from the active layer 23 passesthrough the first conductivity type semiconductor layer 21 to be emittedoutwardly, for example, a flip-chip type light emitting device in whichthe first and second electrodes 21 a and 22 a are mounted toward a leadframe of a package, the ohmic electrode layer 22 b may be formed of alight reflective material, for example, a highly reflective metal.However, the ohmic electrode layer 22 b is not necessarily required inthe exemplary embodiment and in some cases, it may be excluded.

In the case of the structure illustrated in FIG. 1, the first and secondelectrodes 21 a and 22 a are disposed on upper surfaces of the firstconductivity type semiconductor layer 21 and the ohmic electrode layer22 b, respectively, but such an electrode formation scheme is onlyprovided by way of example. Electrodes may be formed at variouspositions of the semiconductor laminate including the first and secondconductivity type semiconductor layers 21 and 22 and the active layer23.

FIGS. 5A through 5G are diagrams each illustrating energy band gaps in apartial laminate structure of a semiconductor light emitting deviceaccording to a modified example modified from FIG. 1.

Referring to FIG. 5A, a hole-diffusion layer 26 disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have three layers 26 a, 26 b and 26 c havingdifferent energy band gaps Eg and different specific resistance levels.The three layers 26 a, 26 b and 26 c of the hole-diffusion layer 26 maybe formed of different nitride semiconductor compounds. Thehole-diffusion layer 26 may include a first layer 26 a formed of GaN, asecond layer 26 b formed of In_(x1)Ga_(1−x1)N (0<x1<1), and a thirdlayer 26 c formed of Al_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposedon the electron-blocking layer 24. Thus, an energy band gap Eg of thesecond layer 26 b may be the smallest and an energy band gap Eg of thethird layer 26 c may be the largest.

Meanwhile, in the exemplary embodiment, x1 in the In composition of thesecond layer 26 b may be less than y1 in the In composition of thequantum well layer 23 a of the active layer 23. However, the presentinventive concept is not limited thereto and depending on exemplaryembodiments, x1 in the In composition of the second layer 26 b may begreater than y1 in the In composition of the quantum well layer 23 a ofthe active layer 23. In the exemplary embodiment, x2 in the Alcomposition of the third layer 26 c may be less than r in the Alcomposition of the electron-blocking layer 24.

Since the first layer 26 a, the second layer 26 b, and the third layer26 c are formed of different compositional compounds as described above,they may have different specific resistance levels even in the case thatthey are undoped with a dopant or are doped with a dopant at the sameconcentration. Meanwhile, the first layer 26 a, the second layer 26 b,and the third layer 26 c are doped with a p-type dopant at differentconcentrations, whereby they may have different specific resistancelevels. At least one layer from among the first layer 26 a, the secondlayer 26 b, and the third layer 26 c may not contain an intentionallydoped dopant. For example, in the exemplary embodiment, the third layer26 c may be a GaN semiconductor layer containing Al without anintentionally doped dopant.

Thicknesses of the first layer 26 a, the second layer 26 b, and thethird layer 26 c forming the hole-diffusion layer 26 may beappropriately determined within a range of 5 nm to 30 nm inconsideration of electrical resistance levels or crystalline defectscaused by lattice mismatches in the respective layers. In the exemplaryembodiment, the thickness of the second layer 26 b having the smallestenergy band gap Eg is the smallest, while the thickness of the thirdlayer 26 c having the largest energy band gap Eg is the greatest.

Referring to FIG. 5B, a hole-diffusion layer 27 disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have three layers 27 a, 27 b and 27 c havingdifferent energy band gaps Eg and different specific resistance levels.The three layers 27 a, 27 b and 27 c of the hole-diffusion layer 27 maybe formed of different nitride semiconductor compounds. In the exemplaryembodiment, the hole-diffusion layer 27 may include a first layer 27 aformed of GaN, a second layer 27 b formed of Al_(x2)Ga_(1−x2)N (0<x2<1),and a third layer 27 c formed of In_(x1)Ga_(1−x1)N (0<x1<1),sequentially disposed on the electron-blocking layer 24. Thus, an energyband gap Eg of the third layer 27 c may be the smallest and an energyband gap Eg of the second layer 27 b may be the largest.

Meanwhile, in the exemplary embodiment, x1 in the In composition of thethird layer 27 c may be less than y1 in the In composition of thequantum well layer 23 a of the active layer 23. However, the presentinventive concept is not limited thereto and depending on exemplaryembodiments, x1 in the In composition of the third layer 27 c may begreater than y1 in the In composition of the quantum well layer 23 a ofthe active layer 23. In the exemplary embodiment, x2 in the Alcomposition of the second layer 27 b may be less than r in the Alcomposition of the electron-blocking layer 24.

Since the first layer 27 a, the second layer 27 b, and the third layer27 c are formed of different compositional compounds as described above,they may have different specific resistance levels even in the case thatthey are undoped with a dopant or are doped with a dopant at the sameconcentration. Meanwhile, the first layer 27 a, the second layer 27 b,and the third layer 27 c are doped with a p-type dopant at differentconcentrations, whereby they may have different specific resistancelevels. At least one layer from among the first layer 27 a, the secondlayer 27 b, and the third layer 27 c may not contain an intentionallydoped dopant. For example, in the exemplary embodiment, the second layer27 b may be a GaN semiconductor layer containing Al without anintentionally doped dopant.

Thicknesses of the first layer 27 a, the second layer 27 b, and thethird layer 27 c forming the hole-diffusion layer 27 may beappropriately determined within a range of 5 nm to 30 nm inconsideration of electrical resistance levels or crystalline defectscaused by lattice mismatches in the respective layers. In the exemplaryembodiment, the thickness of the third layer 27 c having the smallestenergy band gap Eg is the smallest, while the thickness of the secondlayer 27 b having the largest energy band gap Eg is the greatest.

Referring to FIG. 5C, a hole-diffusion layer 28 disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have four layers 28 a, 28 b, 28 c, and 28 dhaving different energy band gaps Eg and different specific resistancelevels. The four layers 28 a, 28 b, 28 c, and 28 d of the hole-diffusionlayer 28 may be formed of different nitride semiconductor compounds. Inthe exemplary embodiment, the hole-diffusion layer 28 may include afirst layer 28 a formed of In_(x1)Ga_(1−x1)N (0<x1<1), a second layer 28b formed of GaN, a third layer 28 c formed of In_(x3)Ga_(1−x3)N(0<x3<1), and a fourth layer 28 d formed of Al_(x2)Ga_(1−x2)N (0<x2<1).In the exemplary embodiment, as illustrated in FIG. 5C, x1 in the Incomposition of the first layer may be identical to x3 in the Incomposition of the third layer. Thus, energy band gaps Eg of the firstand third layers 28 a and 28 c may be the smallest and an energy bandgap Eg of the fourth layer 28 d may be the largest. However, the presentinventive concept is not limited thereto, and, depending on exemplaryembodiments, x1 in the In composition of the first layer may be greateror less than x3 in the In composition of the third layer.

Meanwhile, in the exemplary embodiment, x1 in the In composition of thefirst layer 28 a and x3 in the In composition of the third layer 28 cmay be less than y1 in the In composition of the quantum well layer 23 aof the active layer 23. However, the present inventive concept is notlimited thereto and depending on exemplary embodiments, x1 in the Incomposition of the first layer 28 a and x3 in the In composition of thethird layer 28 c may be greater than y1 in the In composition of thequantum well layer 23 a of the active layer 23. In the exemplaryembodiment, x2 in the Al composition of the fourth layer 28 d may beless than r in the Al composition of the electron-blocking layer 24.

Since the first to fourth layers 28 a, 28 b, 28 c, and 28 d are formedof different compositional compounds as described above, they may havedifferent specific resistance levels even in the case that they areundoped with a dopant or are doped with a dopant at the sameconcentration. Meanwhile, the first to fourth layers 28 a, 28 b, 28 c,and 28 d are doped with a p-type dopant at different concentrations,whereby they may have different specific resistance levels. At least onelayer from among the first to fourth layers 28 a, 28 b, 28 c, and 28 dmay not contain an intentionally doped dopant. For example, in theexemplary embodiment, the fourth layer 28 d may be a GaN semiconductorlayer containing Al without an intentionally doped dopant.

Referring to FIG. 5D, a hole-diffusion layer 25′ disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have three layers 25 a, 25 b and 25 c′ havingdifferent energy band gaps Eg and different specific resistance levels.

The three layers 25 a, 25 b and 25 c′ of the hole-diffusion layer 25′may be formed of different nitride semiconductor compounds. In theexemplary embodiment, the hole-diffusion layer 25′ may include a firstlayer 25 a formed of In_(x1)Ga_(1−x1)N (0<x1<1), a second layer 25 bformed of GaN, and a third layer 25 c′ formed of Al_(x2)Ga_(1−x2)N(0<x2<1), sequentially disposed on the electron-blocking layer 24. Thus,an energy band gap Eg of the first layer 25 a may be the smallest and anenergy band gap Eg of the third layer 25 c′ may be the largest.

Although the exemplary embodiment is mostly the same as the foregoingembodiment described with reference to FIG. 2, x2 in the Al compositionof the third layer 25 c′ may be reduced in a direction away from theactive layer 23. In the exemplary embodiment, x2 in the Al compositionof the third layer 25 c′ may be less than r in the Al composition of theelectron-blocking layer 24.

Referring to FIG. 5E, a hole-diffusion layer 26′ disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have three layers 26 a, 26 b and 26 c′ havingdifferent energy band gaps Eg and different specific resistance levels.

The three layers 26 a, 26 b and 26 c′ of the hole-diffusion layer 26′may be formed of different nitride semiconductor compounds. Thehole-diffusion layer 26′ may include a first layer 26 a formed of GaN, asecond layer 26 b formed of In_(x1)Ga_(1−x1)N (0<x1<1), and a thirdlayer 26 c′ formed of Al_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposedon the electron-blocking layer 24. Thus, an energy band gap Eg of thesecond layer 26 b may be the smallest and an energy band gap Eg of thethird layer 26 c′ may be the largest.

Although the exemplary embodiment is mostly the same as the foregoingembodiment described with reference to FIG. 5A, x2 in the Al compositionof the third layer 26 c′ may be reduced in a direction away from theactive layer 23. In the exemplary embodiment, x2 in the Al compositionof the third layer 26 c′ may be less than r in the Al composition of theelectron-blocking layer 24.

Referring to FIG. 5F, a hole-diffusion layer 27′ disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have three layers 27 a, 27 b′ and 27 c havingdifferent energy band gaps Eg and different specific resistance levels.The three layers 27 a, 27 b′ and 27 c of the hole-diffusion layer 27′may be formed of different nitride semiconductor compounds. Thehole-diffusion layer 27′ may include a first layer 27 a formed of GaN, asecond layer 27 b′ formed of Al_(x2)Ga_(1−x2)N (0<x2<1), and a thirdlayer 27 c formed of In_(x1)Ga_(1−x1)N (0<x1<1), sequentially disposedon the electron-blocking layer 24. Thus, an energy band gap Eg of thethird layer 27 c may be the smallest and an energy band gap Eg of thesecond layer 27 b′ may be the largest.

Although the exemplary embodiment is mostly the same as the foregoingembodiment described with reference to FIG. 5B, x2 in the Al compositionof the second layer 27 b′ may be reduced in a direction away from theactive layer 23. In the exemplary embodiment, x2 in the Al compositionof the second layer 27 b′ may be less than r in the Al composition ofthe electron-blocking layer 24.

Referring to FIG. 5G, a hole-diffusion layer 28′ disposed between theelectron-blocking layer 24 and the second conductivity typesemiconductor layer 22 may have four layers 28 a, 28 b, 28 c, and 28 d′having different energy band gaps Eg and different specific resistancelevels. The four layers 28 a, 28 b, 28 c, and 28 d′ of thehole-diffusion layer 28′ may be formed of different nitridesemiconductor compounds. In the exemplary embodiment, the hole-diffusionlayer 28′ may include a first layer 28 a formed of In_(x1)Ga_(1−x1)N(0<x1<1), a second layer 28 b formed of GaN, a third layer 28 c formedof In_(x3)Ga_(1−x3)N (0<x3<1), and a fourth layer 28 d′ formed ofAl_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposed on theelectron-blocking layer 24.

Although the exemplary embodiment is mostly the same as the foregoingembodiment described with reference to FIG. 5C, x2 in the Al compositionof the fourth layer 28 d′ may be reduced in a direction away from theactive layer 23. In the exemplary embodiment, x2 in the Al compositionof the fourth layer 28 d′ may be less than r in the Al composition ofthe electron-blocking layer 24.

FIGS. 6 through 9 are cross-sectional views illustrating various formsof semiconductor light emitting devices employable in other exemplaryembodiments of the present inventive concept.

Referring to FIG. 6, a semiconductor light emitting device 200 accordingto another exemplary embodiment of the present inventive concept mayinclude a diffusion barrier layer disposed between the active layer 23and the electron-blocking layer 24.

When p-type dopant atoms are diffused to the active layer 23,nonradiative recombination may be increased and crystallinity of theactive layer 23 may be degraded. The diffusion barrier layer 30 may bedisposed between the active layer 23 and the electron-blocking layer 24to thereby prevent p-type dopant atoms contained in the secondconductivity type semiconductor layer 22 and/or the electron-blockinglayer 24 from being diffused to the active layer 23.

In order to perform such functions, the diffusion barrier layer 30 maycontain a semiconductor material formed of Al_(c)In_(d)Ga_(1−c−d)N(0≦c<1, 0≦d<1, 0≦c+d≦1). The diffusion barrier layer 30 may be formed ofan undoped semiconductor. Here, the term “undoped” refers to anintentionally undoped state.

In addition, c in the Al composition may be less than x in the Alcomposition contained in a lower region of the electron-blocking layer24 adjacent to the diffusion barrier layer 30. Further, c in the Alcomposition may be increased in a direction away from the active layer23.

The diffusion barrier layer 30 may have an energy band gap greater thanan energy band gap of the active layer 23 and the second conductivitytype semiconductor layer 22, and may perform functions of effectivelysuppressing the overflow of electrons, together with theelectron-blocking layer 24.

As the diffusion barrier layer 30 prevents the diffusion of the p-typedopant atoms, a concentration of the p-type dopant atoms may beincreased in the electron-blocking layer 24 or the second conductivitytype semiconductor layer 22. Accordingly, a sufficient concentration ofthe p-type dopant atoms may be ensured to allow for an increase in thenumber of electrons participating in light emission, whereby lightemitting characteristics may be further improved.

Referring to FIG. 7, a semiconductor light emitting device 300 accordingto another exemplary embodiment of the present inventive concept mayinclude a light emitting structure formed on a conductive substrate 110.The light emitting structure may include a second conductivity typesemiconductor layer 122, an active layer 123, and a first conductivitytype semiconductor layer 121 that are sequentially stacked on theconductive substrate 110, and an electron-blocking layer 124 providedbetween the active layer 123 and the second conductivity typesemiconductor layer 122. In the exemplary embodiment, the light emittingstructure may further include a hole-diffusion layer 125 between theelectron-blocking layer 124 and the second conductivity typesemiconductor layer 122. The hole-diffusion layer 125 may have thematerial and energy band gap structure described with reference to FIGS.1 and 2. In addition, depending on exemplary embodiments, thehole-diffusion layer 125 may have the material and energy band gapstructure described with reference to FIGS. 5A through 5G. Accordingly,light emission efficiency and light output characteristics may beimproved.

The first conductivity type semiconductor layer 121 may be, for example,an n-type semiconductor layer, and a first electrode 121 a may be formedon an upper portion of the first conductivity type semiconductor layer121. The second conductivity type semiconductor layer 122 may be, forexample, a p-type semiconductor layer, and a reflective metal layer 122a may be disposed between the second conductivity type semiconductorlayer 122 and the conductive substrate 110. The reflective metal layer122 a may be formed of a material exhibiting electrical ohmiccharacteristics with respect to the second conductivity typesemiconductor layer 122 and further, may be formed of a highlyreflective metal. In consideration of such functions, the reflectivemetal layer 122 a may be formed to contain a material such as Ag, Ni,Al, Rh, Pd, Ir, Ru, Mg, Zn Pt, Au or the like.

The conductive substrate 110 may be connected to an external powersource and serve to apply driving power to the second conductivity typesemiconductor layer 122. In addition, the conductive substrate 110 mayserve as a support supporting the light emitting structure in a processfor removing a growth substrate used in a semiconductor growth, such asa laser lift-off (LLO) process. The conductive substrate 110 may beformed of a material containing one of Au, Ni, Al, Cu, W, Si, Se, andGaAs and for example, may be formed by doping a Si substrate with Al. Inthis case, the conductive substrate 110 may be formed on the reflectivemetal layer through a process such as a plating process, sputteringprocess, a deposition process or the like. Unlike this, the conductivesubstrate 110 that has been previously manufactured may be bonded to thereflective metal layer 122 a by using a conductive bonding layer or thelike.

Referring to FIG. 8, a semiconductor light emitting device 400 accordingto another exemplary embodiment of the present inventive concept mayinclude a first conductivity type semiconductor layer 221, an activelayer 223, an electron-blocking layer 224, a hole-diffusion layer 225, asecond conductivity type semiconductor layer 222, a second electrodelayer 222 b, a first electrode layer 221 a connected to the firstconductivity type semiconductor layer 221, and a substrate 210. In thiscase, to electrically connect the first electrode layer 221 a to thefirst conductivity type semiconductor layer 221, the first electrodelayer 221 a may include one or more conductive vias V penetratingthrough the second electrode layer 222 b, the second conductivity typesemiconductor layer 222, the hole-diffusion layer 225, theelectron-blocking layer 224, and the active layer 223 to be extendedfrom one surface of the first electrode layer 221 a to at least aportion of the first conductivity type semiconductor layer 221. However,since the conductive vias V may be provided for electrical connectionand current dispersion of the first conductivity type semiconductorlayer 221 and accordingly, the purpose of the conductive vias V may beachieved as long as the conductive vias V come into contact with thefirst conductivity type semiconductor layer 221, it may be unnecessaryto extend the conductive vias V to an external surface of the firstconductivity type semiconductor layer 221.

The hole-diffusion layer 225 may have the material and energy band gapstructure described with reference to FIGS. 1 and 2. In addition,depending on exemplary embodiments, the hole-diffusion layer 225 mayhave the material and energy band gap structure described with referenceto FIGS. 5A and 5G. Thus, light emission efficiency and light outputcharacteristics may be improved. In addition, according to the exemplaryembodiment, current dispersion characteristics may be improved andadvantageous effects may be obtained in terms of heat radiation.

The first conductivity type semiconductor layer 221 may be electricallyconnected to the substrate 210 via the conductive vias V and the number,shape, pitch or the like, of the conductive vias V may be appropriatelyadjusted in order to decrease contact resistance. For example, thenumber, shape, pitch or the like, of the conductive vias V may beapplied as in the exemplary embodiment of FIG. 8.

For electrical insulation, an insulating layer 240 may be disposed onside surfaces of the conductive vias V and the second electrode layer222 b. Since a material of the insulating layer 240 is employable, aslong as it has electrical insulating properties, but it is preferable toabsorb light to the smallest, the material of the insulating layer 240may be, for example, a silicon oxide or a silicon nitride such as SiO₂,SiO_(x)N_(y), Si_(x)N_(y) or the like.

The second electrode layer 222 b disposed on the second conductivitytype semiconductor layer 222 may be formed of at least one materialselected from among Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au and thelike, in consideration of light reflective functions and ohmic contactcharacteristics with respect to the second conductivity typesemiconductor layer 222. In order to increase light reflectivefunctions, a distributed Bragg reflector (DBR) having a plurality oflayers of TiO₂/SiO₂ or SiO₂/Ta₂O₅ pairs may be further included betweenan ohmic electrode layer and the substrate. The second electrode layer222 b may be formed using a physical deposition such as a sputteringprocess or a chemical deposition.

A second electrode 222 a may be disposed on the second electrode layer222 b exposed by mesa etching, and the second electrode layer 222 b maybe electrically connected to the second electrode 222 a and receivedriving power from the outside.

Although not limited thereto, the substrate 210 may be formed of amaterial containing one of Au, Ni, Al, Cu, W, Si, Se, GaAs, SiAl, Ge,SiC, AlN, GaN, and AlGaN and may be formed through a process such as aplating process, a sputtering process, a deposition process, a bondingprocess or the like.

Referring to FIG. 9, a semiconductor light emitting device 500 accordingto another exemplary embodiment of the present inventive concept mayinclude first and second electrode pads 315 a and 315 b connected tofirst and second conductivity type semiconductor layers 321 and 322,respectively. The first electrode pad 315 a may include a conductive via3151 a penetrating through a second conductivity type semiconductorlayer 322, a hole-diffusion layer 325, an electron-blocking layer 324,and an active layer 325 to be connected to the first conductivity typesemiconductor layer 321, and an electrode extension part 3152 aconnected to the conductive via 3151 a. The conductive via 3151 a may besurrounded by an insulating layer 316 to be electrically separated fromthe active layer 323, the electron-blocking layer 324, thehole-diffusion layer 325, and the second conductivity type semiconductorlayer 322. The conductive via 3151 a may be disposed in an etched regionof the semiconductor laminate.

The hole-diffusion layer 325 may have the material and energy band gapstructure described with reference to FIGS. 1 and 2. In addition,depending on exemplary embodiments, the hole-diffusion layer 325 mayhave the material and energy band gap structure described with referenceto FIGS. 5A through 5G. Accordingly, light emission efficiency and lightoutput characteristics may be improved.

The number, shape, or pitch of the conductive vias 3151 a or a contactarea thereof with respect to the first conductivity type semiconductorlayer 321 may be appropriately designed so as to reduce contactresistance. Further, the conductive vias 3151 a may be arranged in amatrix form on the semiconductor laminate, whereby a current flow may beimproved. The second electrode pad 315 b may include an ohmic contactlayer 3151 b and an electrode extension part 3152 b on the secondconductivity type semiconductor layer 322. The number of the conductivevias 3151 a or the contact area thereof may be appropriately designedsuch that a planar contact area between a plurality of the conductivevias 3151 a arranged in rows and columns and the first conductivity typesemiconductor layer 321 may range from 0.5% to 20% of the overall planararea of the light emitting laminate. A diameter DV of each conductivevia 3151 a in the contact area coming into contact with the firstconductivity type semiconductor layer 321 may be, for example,approximately 5 μm to 50 μm. The number of the conductive vias 3151 amay be 3 to 300 per region of the light emitting laminate, depending onan area of the region of the light emitting laminate. The number of theconductive vias 3151 a may preferably be 4 or more per region of thelight emitting laminate, but may be varied depending on an area of theregion of the light emitting laminate. Distances between the respectiveconductive vias 3151 a may have a matrix structure having rows andcolumns of 100 μm to 500 μm, preferably, rows and columns of 150 μm to450 μm. In the case that the distances between the respective conductivevias 3151 a are smaller than 100 μm, the number of the conductive vias3151 a may be increased while a light emitting area may be relativelyreduced, thereby leading to a decrease in light emission efficiency. Inthe case that the distances between the respective conductive vias 3151a are greater than 500 μm, current dispersion may not be facilitated todeteriorate light emission efficiency. Depths of the conductive vias3151 a may be differently formed depending on thicknesses of the secondconductivity type semiconductor layer 322, the hole-diffusion layer 325,the electron-blocking layer 324, and the active layer 323 and forexample, may be range from 0.5 μm to 5.0 μm.

FIGS. 10 and 11 are cross-sectional views of light emitting devicepackages illustrating examples in which the semiconductor light emittingdevice according to an exemplary embodiment of the present inventiveconcept is applied to the packages.

Referring to FIG. 10, a semiconductor light emitting device package 1000may include a semiconductor light emitting device 1001, a package body1002 and a pair of lead frames 1003. The semiconductor light emittingdevice 1001 may be mounted on the lead frame 1003 to be electricallyconnected thereto through a wire W. Depending on embodiments, thesemiconductor light emitting device 1001 may be mounted on anotherportion of the package 1000 rather than the lead frame 1003, forexample, on the package body 1002. The package body 1002 may have a cupshape in order to improve light reflection efficiency, and such areflective cup may be filled with an encapsulant 1005 containing a lighttransmissive material in order to encapsulate the semiconductor lightemitting device 1001 and the wire W. In the embodiment, thesemiconductor light emitting device package 1000 may include thesemiconductor light emitting devices according to the foregoingembodiments. Depending on exemplary embodiments, the package body 1002and/or the encapsulant 1005 may formed of a black material. Ifnecessary, a black material may be coated on an upper surface of thepackage, such that the package may externally seems to be black. Theblack package as described above may be employed in display devices suchas an electronic display and the like.

In another example, a package formed by molding a semiconductor lightemitting device mounted on a circuit board such as a PCB, using a blacktransparent resin may be employed in display devices such as anelectronic display and the like.

The black package may include a blue light emitting device and/or agreen light emitting device, and a red light emitting device having thestructure of the light emitting device according to the exemplaryembodiment of the present inventive concept.

Referring to FIG. 11, a semiconductor light emitting device package 2000may include a semiconductor light emitting device 2001, a mounting board2010 and an encapsulant 2003. In addition, a wavelength conversion part2002 may be formed on a surface and/or side surfaces of thesemiconductor light emitting device 2001. The semiconductor lightemitting device 2001 may be mounted on the mounting board 2010 and beelectrically connected thereto through a wire W. According to exemplaryembodiment, the semiconductor light emitting device 2001 may be mountedon the mounting board 2010 through flip chip bonding.

The mounting board 2010 may include a substrate body 2011, an uppersurface electrode 2013, and a lower surface electrode 2014. In addition,the mounting board 2010 may also include a through electrode 2012connecting the upper surface electrode 2013 and the lower surfaceelectrode 2014. The mounting board 2010 may be provided as a board suchas PCB, MCPCB, MPCB, FPCB or the like and a structure thereof may beused in various manners.

In a case in which the semiconductor light emitting device 2001 emits UVlight or blue light, the wavelength conversion part 2002 may include atleast one of blue, yellow, green and red phosphors and may combine theblue light emitted from the semiconductor light emitting device 2001with light from the phosphor to thereby emit white light or may emityellow, green or red light. A color temperature and a color renderingindex (CRI) of white light may be adjusted by using a white lightemitting module formed by combining a light emitting device packageemitting white light with a package emitting yellow, green or red light.In addition, the light emitting device package may be configured toinclude at least one of light emitting devices emitting violet, blue,green, red and ultraviolet light. In this case, in a light emittingdevice package or a module product formed by combining light emittingdevice packages, a color rendering index (CRI) may be adjusted from 40to 100 on a level of solar light, and various types of white light withcolor temperatures ranging from 2000K to 20000K may be generated. Also,if necessary, the light emitting device package or the module productformed by combining light emitting device packages may generate violet,blue, green, red or orange visible light or infrared light to adjust thecolor of light according to a surrounding atmosphere and a user mood.Also, the light emitting device package or the module product maygenerate a specific wavelength of light for accelerating the growth ofplants.

White light formed by combining yellow, green, red phosphors with a bluelight emitting device and/or combining green and red light emittingdevices may have two or more peak wavelengths, and coordinates (x, y)thereof in the CIE 1931 coordinate system of FIG. 12 may be positionedon a line segment connecting (0.4476, 0.4074), (0.3484, 0.3516),(0.3101, 0.3162), (0.3128, 0.3292), and (0.3333, 0.3333). Alternatively,coordinates (x, y) thereof in the CIE 1931 coordinate system may bepositioned in a region surrounded by the line segment and blackbodyradiation spectrum. The color temperature of white light may range from2000K to 20000K.

The wavelength conversion part 2002 may contain phosphors or quantumdots.

The phosphors may have the following compositional formulae and colors.

Oxides: yellow and green Y₃Al₅O₁₂:Ce, Tb₃Al₅O₁₂:Ce, Lu₃Al₅O₁₂:Ce

Silicates: yellow and green (Ba,Sr)₂SiO₄:Eu, yellow and orange(Ba,Sr)₃SiO₅:Ce, red Ca₂SiO₄:Eu, Ca_(1.2)Eu_(0.8)SiO₄

Nitrides: green β-SiAlON:Eu, yellow La₃Si₆N₁₁:Ce, orange α-SiAlON:Eu,red CaAlSiN₃:Eu, Sr₂Si₅N₈:Eu, SrSiAl₄N₇:Eu, SrLiAl₃N₄:Eu,Ln_(4−x)(Eu_(z)M_(1−z))_(x)Si_(12−y)Al_(y)O_(3+x+y)N_(18−x−y) (0.5≦x≦3,0<z<0.3, 0<y≦4) (where, Ln is at least one element selected from a groupconsisting of group IIIa elements and rare-earth elements, and M is atleast one element selected from a group consisting of Ca, Ba, Sr and Mg)

Fluorides: KSF based red K₂SiF₆:Mn⁴⁺, K₂TiF₆:Mn⁴⁺, NaYF₄:Mn⁴⁺,NaGdF₄:Mn⁴⁺

The phosphor composition may basically accord with stoichiometry andrespective elements may be substituted with other elements withinrespective groups in a periodic table of the elements. For example, Srmay be substituted with Ba, Ca, Mg or the like within the alkaline earthgroup (II) and Y may be substituted with lanthanum (La) based elementssuch as Tb, Lu, Sc, Gd or the like. In addition, Eu or the like, anactivator, may be substituted with Ce, Tb, Pr, Er, Yb or the likeaccording to a desired energy level. The activator may be used alone ora co-activator or the like may be added in order to allow formodification of properties.

Further, as a material for substituting for the phosphor, a materialsuch as a quantum dot (QD) or the like may be used, and the QD or thephosphor may be used alone or a combination of the phosphor and the QDmay be used.

The quantum dot (QD) may be configured to have a core (3˜10 nm) formedof CdSe, InP, or the like, a shell (0.5˜2 nm) formed of ZnS, ZnSe or thelike, and a ligand structure stabilizing the core and the shell, and mayimplement various colors depending on a size thereof.

The following Table 1 shows types of phosphors in a white light emittingdevice package using a UV light emitting device chip (200˜440 nm) or ablue light emitting device chip (440˜480 nm) according to applicationfields.

TABLE 1 USAGE Phosphor LED TV BLU β-SiAlON:Eu²⁺, (Ca, Sr)AlSiN₃:Eu²⁺,La₃Si₆N₁₁:Ce³⁺, K₂SiF₆:Mn⁴⁺, SrLiAl₃N₄:Eu,Ln_(4−x)(Eu_(z)M_(1−z))_(x)Si_(12−y)Al_(y)O_(3+x+y)N_(18−x−y)(0.5 ≦ x ≦3, 0 < z < 0.3, 0 < y ≦ 4), K₂TiF₆:Mn⁴⁺, NaYF₄:Mn⁴⁺, NaGdF₄:Mn⁴⁺Ca₂SiO₄:Eu, Ca_(1.2)Eu_(0.8)SiO₄ Lighting Lu₃Al₅O₁₂:Ce³⁺,Ca-α-SiAlON:Eu²⁺, Apparatuses La₃Si₆N₁₁:Ce³⁺, (Ca, Sr)AlSiN₃:Eu²⁺,Y₃Al₅O₁₂:Ce³⁺, K₂SiF₆:Mn⁴⁺, SrLiAl₃N₄:Eu,Ln_(4−x)(Eu_(z)M_(1−z))_(x)Si_(12−y)Al_(y)O_(3+x+y)N_(18−x−y)(0.5 ≦ x ≦3, 0 < z < 0.3, 0 < y ≦ 4), K₂TiF₆:Mn⁴⁺, NaYF₄:Mn⁴⁺, NaGdF₄:Mn⁴⁺,Ca₂SiO₄:Eu, Ca_(1.2)Eu_(0.8)SiO₄ Side View Lu₃Al₅O₁₂:Ce³⁺,Ca-α-SiAlON:Eu²⁺, (Mobile Devices, La₃Si₆N₁₁:Ce³⁺, (Ca, Sr)AlSiN₃:Eu²⁺,Laptop PC) Y₃Al₅O₁₂:Ce³⁺, (Sr, Ba, Ca, Mg)₂SiO₄:Eu²⁺, K₂SiF₆:Mn⁴⁺,SrLiAl₃N₄:Eu,Ln_(4−x)(Eu_(z)M_(1−z))_(x)Si_(12−y)Al_(y)O_(3+x+y)N_(18−x−y)(0.5 ≦ x ≦3, 0 < z < 0.3, 0 < y ≦ 4), K₂TiF₆:Mn⁴⁺, NaYF₄:Mn⁴⁺, NaGdF₄:Mn⁴⁺,Ca₂SiO₄:Eu, Ca_(1.2)Eu_(0.8)SiO₄ Electronic Lu₃Al₅O₁₂:Ce³⁺,Ca-α-SiAlON:Eu²⁺, Apparatuses La₃Si₆N₁₁:Ce³⁺, (Ca, Sr)AlSiN₃:Eu²⁺,(Headlamps, etc.) Y₃Al₅O₁₂:Ce³⁺, K₂SiF₆:Mn⁴⁺, SrLiAl₃N₄:Eu,Ln_(4−x)(Eu_(z)M_(1−z))_(x)Si_(12−y)Al_(y)O_(3+x+y)N_(18−x−y)(0.5 ≦ x ≦3, 0 < z < 0.3, 0 < y ≦ 4), K₂TiF₆:Mn⁴⁺, NaYF₄:Mn⁴⁺, NaGdF₄:Mn⁴⁺,Ca₂SiO₄:Eu, Ca_(1.2)Eu_(0.8)SiO₄

The encapsulant 2003 may have a convex lens shape in which an uppersurface thereof is upwardly convex, but may have a concave lens shapeaccording to embodiments, whereby an orientation angle of light emittedthrough an upper surface of the encapsulant 2003 may be controlled.

In the exemplary embodiment, the semiconductor light emitting devicepackage 2000 may include the semiconductor light emitting devicesaccording to the foregoing embodiments.

FIGS. 13 and 14 each illustrate a light source module employable in alighting device according to an exemplary embodiment of the presentinventive concept.

Referring to FIG. 13, a white light emitting device package W1 having acolor temperature of 4000K, a white light emitting device package W2having a color temperature of 3000K, and a red light emitting devicepackage R having a color temperature of 3000K may be disposed within awhite light emitting device package module. By combining the lightemitting device packages, a white light emitting device package modulein which a color temperature thereof may be adjusted within a range of2000K to 4000K and a color rendering index Ra thereof is 85 to 99 may bemanufactured. The module may be employed in a bulb-type lamp of FIG. 17and the like.

Referring to FIG. 14, a white light emitting device package W3 having acolor temperature of 5000K and a white light emitting device package W4having a color temperature of 2700K may be disposed within a white lightemitting device package module. By combining the light emitting devicepackages, a white light emitting device package module in which a colortemperature thereof may be adjusted within a range of 2700K to 5000K anda color rendering index Ra thereof is 85 to 99 may be manufactured. Themodule may be employed in a bulb-type lamp of FIG. 17 and the like.

The number of light emitting device packages may be varied depending ona basic, predetermined value of a color temperature. In the case thatthe basic, predetermined value of the color temperature is in thevicinity of 4000K, the number of light emitting device packagescorresponding to the color temperature of 4000K may be greater than thatof light emitting device packages having a color temperature of 3000K orred light emitting device packages.

FIGS. 15 and 16 are cross-sectional views each illustrating an examplein which the semiconductor light emitting device according to anexemplary embodiment of the present inventive concept is applied to abacklight unit.

Referring to FIG. 15, a backlight unit 3000 may include a light source3001 mounted on a substrate 3002 and at least one optical sheet 3003disposed thereabove. The light source 3001 may be provided in the formof a chip-on-board (COB) type structure in which at least onesemiconductor light emitting device according to the foregoingembodiments may be directly mounted on the substrate 3002.Alternatively, the semiconductor light emitting device package 2000 maybe used.

The light source 3001 in the backlight unit 3000 of FIG. 15 emits lighttoward a liquid crystal display (LCD) device disposed thereabove. On theother hand, a light source 4001 mounted on a substrate 4002 in abacklight unit 4000 according to another embodiment illustrated in FIG.16 emits light laterally and the emitted light is incident to a lightguide plate 4003 and may be converted into the form of a surface lightsource. The light having passed through the light guide plate 4003 maybe emitted upwardly and a reflective layer 4004 may be formed under abottom surface of the light guide plate 4003 in order to improve lightextraction efficiency.

FIGS. 17 and 18 each illustrate an example in which the semiconductorlight emitting device according to an exemplary embodiment of thepresent inventive concept is applied to the lighting device.

Referring to an exploded perspective view of FIG. 17, a lighting device5000 is exemplified as a bulb-type lamp, and includes a light emittingmodule 5003, a driving unit 5008 and an external connector unit 5010. Inaddition, exterior structures such as an external housing 5006, aninternal housing 5009, a cover unit 5007 and the like may beadditionally included. The light emitting module 5003 may include alight source 5001 and a circuit board 5002 having the light source 5001mounted thereon. The light source 5001 may be the semiconductor lightemitting device, the light emitting device package or the like describedin the foregoing embodiment.

The embodiment illustrates the case in which a single light source 5001is mounted on the circuit board 5002; however, if necessary, a pluralityof light sources may be mounted thereon.

In addition, in the lighting device 5000, the light emitting module 5003may include the external housing 5006 serving as a heat radiating partand including a heat sink plate 5004 in direct contact with the lightemitting module 5003 to improve the dissipation of heat. In addition,the lighting device 5000 may include the cover unit 5007 mounted abovethe light emitting module 5003 and having a convex lens shape. Thedriving unit 5008 may be disposed inside the internal housing 5009 andmay be connected to the external connector unit 5010 such as a socketstructure to receive power from an external power source. In addition,the driving unit 5008 may convert the received power into a currentsource appropriate for driving the light source 5001 of the lightemitting module 5003 and supply the converted current source thereto.For example, the driving unit 5008 may be configured of an AC-DCconverter, a rectifying circuit part, or the like.

Meanwhile, the lighting device in which a light source device isimplemented according to an exemplary embodiment of the presentinventive concept may be a bar-type lamp as illustrated in FIG. 18 andmay have a shape similar to a fluorescent lamp so as to be substitutedwith the fluorescent lamp according to the related art, but is notlimited to having such a shape. The lighting device 5000 may emit lighthaving light characteristics similar to those of the fluorescent lamp.

Referring to the exploded perspective view of FIG. 18, a lighting device6000 according to the exemplary embodiment may include a light sourcepart 6203, a body part 6204, and a driving part 6209 and may furtherinclude a cover part 6207 covering the light source part 6203.

The light source part 6203 may include a substrate 6202 and a pluralityof light sources 6201 mounted on the substrate 6202. A light source 6201may be the semiconductor light emitting device, or the semiconductorlight emitting device package described in the foregoing embodiments.

The body part 6204 may have the light source part 6203 mounted on onesurface thereof to be fixed thereto. The body part 6204 may be a sort ofsupport structure and include a heat sink. The body part 6204 may beformed of a material having high thermal conductivity so as to emit heatgenerated from the light source part 6203 outwardly. For example, thebody part 6204 may be formed of a metal material, but is not limitedthereto.

The body part 6204 may have an elongated bar shape corresponding to ashape of the substrate 6202 of the light source part 6203. The body part6204 may have a recess 6214 formed in a surface thereof on which thelight source part 6203 is mounted, the recess 6214 being capable ofreceiving the light source part 6203 therein.

A plurality of heat radiating fins 6224 for the radiation of heat may beformed on at least one outer side surface of the body part 6204 so as toprotrude therefrom. In addition, a catching groove 6234 may be formed inat least one distal end of the outer side surface disposed above therecess 6214, the catching groove 6234 being extended in a lengthdirection of the body part 6204. The cover part 6207, to be describedlater, may be coupled to the catching groove 6234.

At least one of both ends of the body part 6204 in the length directionmay be opened and thus, the body part 6204 has a pipe shape having atleast one open end.

The driving part 6209 may be provided in at least one open end of theboth ends of the body part 6204 in the length direction and supplydriving power to light source part 6203. The exemplary embodimentillustrates that at least one end of the body part 6204 is opened andhas the driving part 6209 provided therein. However, the presentinventive concept is not limited thereto and for example, the drivingpart 6209 may be coupled to the at least one open end of the body part6204 and cover the open both ends of the body part 6204. The drivingpart 6209 may include outwardly protruded electrode pins 6219.

The cover part 6207 may be coupled to the body part 6204 and cover thelight source part 6203. The cover part 6207 may be formed of a lighttransmissive material.

The cover part 6207 may have a curved semicircular surface to enablelight to be generally externally irradiated in a uniform manner. Inaddition, a bottom surface of the cover part 6207 coupled to the bodypart 6204 thereof may be provided with protrusions 6217 formed in thelength direction of the cover part 6207 and engaged with the catchinggrooves 6234 of the body part 6204.

The exemplary embodiment illustrates that the cover part 6207 has asemicircular shape, but the cover part 6207 is not limited thereto. Forexample, the cover part 6207 may have a flat quadrangular shape and mayalso have other polygonal shapes. Such a shape of the cover part 6207may be variously changed depending on a design of a lighting device fromwhich light is irradiated.

FIG. 19 is an exploded perspective view schematically illustrating alighting device according to another exemplary embodiment of the presentinventive concept.

Referring to FIG. 19, a lighting device 7000 may have a surface lightsource structure and may be configured to include a light source module7210, a housing 7220, a cover 7240 and a heat sink 7250.

The light source module 7210 may be the semiconductor light emittingdevice or the light emitting device package described in the foregoingexemplary embodiment, or the like. Thus, a detailed description thereofwill be omitted. A plurality of light source modules 7210 may bearranged and mounted on a circuit board 7211.

The housing 7220 may have a box shape by including one surface 7222 onwhich the light source module 7210 is mounted and side surfaces 7224extended from edges of one surface 7222. The housing 7220 may be formedof a material having excellent thermal conductivity, for example, ametal, so as to emit heat generated from the light source modules 7210,outwardly.

Holes 7226 may be formed in one surface 7222 of the housing 7220 topenetrate therethrough. The heat sinks 7250 to be described later may beinserted into and coupled to the holes 7226. In addition, the circuitboard 7211 on which the light source modules 7210 are mounted (thecircuit board 7211 to be mounted on one surface 7222) may be partiallydisposed over the holes 7226 to be exposed outwardly.

The cover 7240 may be coupled to the housing 7220 so as to cover thelight source modules 7210 and have a generally flat structure.

The heat sinks 7250 may be fastened into the holes 7226 through theother surface 7225 of the housing 7220. In addition, the heat sinks 7250may come into contact with the light source modules 7210 through theholes 7226 to discharge heat from the light source modules 7210outwardly. In order to improve heat radiation efficiency, the heat sinks7250 may include a plurality of heat radiation fins 7251. The heat sinks7250 may be formed of a material having excellent thermal conductivity,similarly to the housing 7220.

The lighting device using the light emitting device may be classified asan indoor lighting device and an outdoor lighting device. Indoor LEDlighting devices may be generally provided to replace or retrofitexisting lighting devices, and may include bulb type lamps, fluorescentlamps (LED-tubes), and flat type illumination devices. Outdoor LEDlighting devices may include street lamps, security lamps, floodlightinglamps, scenery lamps, traffic lights, and the like.

The lighting device using LEDs may be employed as internal or externallight sources of vehicles. Internal light sources of vehicles mayinclude indoor lights, reading lights, gauge light sources, and thelike. External light sources of vehicles may include various lightsources such as headlights, break lights, turn indicators, fog lights,running lights and the like.

In addition, as light sources used for robots or various mechanicaldevices, LED lighting devices may be used. In particular, LED lightingdevices using specific waveform bands may promote the growth of plantsand may stabilize emotions or treat illnesses in humans.

With reference to FIGS. 20 and 21, a lighting system using the lightingdevice will be described. Alighting system 8000 according to anexemplary embodiment of the present inventive concept may automaticallycontrol a color temperature according to surrounding environments (forexample, temperature and humidity), and may provide a lighting apparatusserving as a mood lighting capable of satisfying human sensibility, notmerely serving as a simple lighting fixture.

FIG. 20 is a block diagram schematically illustrating a lighting systemaccording to an exemplary embodiment of the present inventive concept.

Referring to FIG. 20, the lighting system 8000 according to theexemplary embodiment of the present inventive concept may include asensing unit 8010, a controlling unit 8020, a driving unit 8030, and alighting unit 8040.

The sensing unit 8010 may be installed in indoor and outdoorenvironments and may include a temperature sensor 8011 and a humiditysensor 2012 to measure at least one atmospheric condition among ambienttemperature and humidity. In addition, the sensing unit 8010 maytransfer the measured atmospheric condition, that is, temperature andhumidity information, to the controlling unit 8020 electricallyconnected to the sensing unit 8010.

The controlling unit 8020 may compare the measured atmospherictemperature and humidity with an atmospheric condition (temperature andhumidity range) preset by a user and as a comparison result, maydetermine a color temperature of the lighting unit 8040 corresponding tothe atmospheric condition. The controlling unit 8020 may be electricallyconnected to the driving unit 8030 and control the driving unit 8030 todrive the lighting unit 8040 at the determined color temperature.

FIG. 21 illustrates components of the lighting unit 8040 illustrated inFIG. 20.

Referring to FIG. 21, the lighting unit 8040 may be operated by powersupplied from the driving unit 8030. The lighting unit 8040 may includeat least one of the lighting devices illustrated in FIGS. 17 through 19.For example, the lighting unit 8040 may be configured of first andsecond lighting devices 8041 and 8042 having different colortemperatures from each other and each of the first and second lightingdevices 8041 and 8042 may include a plurality of light emitting devicesemitting the same white light.

The first lighting device 8041 may emit white light having a first colortemperature and the second lighting device 8042 may emit white lighthaving a second color temperature. The first color temperature may belower than the second color temperature or vice versa, that is, thefirst color temperature may be higher than the second color temperature.Here, white light having a relatively low color temperature maycorrespond to warm white light, while white light having a relativelyhigh color temperature may correspond to cold white light. When power issupplied to the first and second lighting devices 8041 and 8042, thefirst and second lighting devices 8041 and 8042 may emit white lighthaving the first color temperature and white light having the secondcolor temperature, respectively. The white light having the first colortemperature and the white light having the second color temperature maybe combined with each other to thereby implement white light having thecolor temperature determined by the controlling unit.

Specifically, when the first color temperature is lower than the secondcolor temperature, in the case that a relatively high color temperatureis determined by the controlling unit, a quantity of light of the firstlighting device 8041 may be reduced while a quantity of light of thesecond lighting device 8042 may be increased, such that combined whitelight may be implemented as having the determined color temperature. Inthis case, quantities of the respective lighting devices 8041 and 8042may be implemented by controlling the quantity of light of all the lightemitting devices through the adjustment of power, or may be implementedby adjusting the number of driven light emitting devices.

FIG. 22 is a flowchart illustrating a method of controlling the lightingsystem shown in FIG. 20. Referring to FIG. 22, first, a user may set acolor temperature through the controlling unit according to thetemperature and humidity range (S510). The set temperature and humiditydata may be stored in the controlling unit.

In general, in the case of a color temperature equal to or higher than6000K, a relatively cold color such as blue may be exhibited, while inthe case of a color temperature of equal to or less than 4000K, arelatively warm color such as red may be exhibited. Thus, in theexemplary embodiment, in the case that temperature and humidity exceed20° C. and 60%, respectively, a user may set the lighting unit to beilluminated at a color temperature of 6000K or more, using thecontrolling unit. In the case that temperature and humidity are 10° C.to 20° C. and 40% to 60%, respectively, a user may set the lighting unitto be illuminated at a color temperature of 4000K to 6000K, using thecontrolling unit. In the case that temperature and humidity are 10° C.or less and 40% or less, respectively, a user may set the lighting unitto be illuminated at a color temperature of 4000K or less, using thecontrolling unit.

Then, the sensing unit may measure at least one of atmospherictemperature and humidity conditions (S520). Information regarding thetemperature and humidity measured by the sensing unit may be transferredto the controlling unit.

Then, the controlling unit may compare measured values transferred fromthe sensing unit with set values (S530). Here, the measured values aredata of the temperature and humidity measured by the sensing unit, andthe set values are data of the temperature and humidity previously setby the user and stored in the controlling unit. That is, the controllingunit may compare the measured temperature and humidity with thepreviously set temperature and humidity.

As comparison result, whether or not the measured values satisfy a setvalue range may be determined (S540). When the measured values satisfythe set value range, a current color temperature may be maintained andtemperature and humidity may be re-measured (S520). Meanwhile, when themeasured values do not satisfy the set value range, set valuescorresponding to the measured values may be detected, and a colortemperature corresponding thereto may be determined (S550). In addition,the controlling unit may control the driving unit to drive the lightingunit at the determined color temperature.

Then, the driving unit may drive the lighting unit to have thedetermined color temperature (S560). That is, the driving unit maysupply the lighting unit with power required for driving the lightingunit to the determined color temperature. Accordingly, the lighting unitmay be controlled to have a color temperature corresponding to thetemperature and humidity previously set by the user according toatmospheric temperature and humidity conditions.

Therefore, the lighting system may automatically control a colortemperature of an indoor lighting unit according to atmospherictemperature and humidity variations, whereby human sensibility variedaccording to environment changes may be satisfied and also,psychological stability may be provided to human beings.

FIG. 23 is an exemplary view schematically illustrating the use of thelighting system shown in FIG. 20. As illustrated in FIG. 23, thelighting unit 8040, an indoor lighting fixture, may be installed on theceiling. In this case, the sensing unit 8010 may be realized as aseparate device in order to measure outdoor temperature and humidity andmay be installed on the outside wall. In addition, the controlling unit8020 may be installed in an indoor space so as to facilitate the user'ssetting and confirmation. However, the lighting system according to theexemplary embodiment is not limited thereto, and the lighting system maybe installed on an inner wall instead of interior lightings or may beapplied to lighting elements and the like such as standing lamps, usablein indoor and outdoor environments.

Optical designs of LED lighting devices may be changed depending onproduct forms, intended locations, and objects thereof. With regard tomood lighting devices, controlling of such lighting devices may beperformed using technologies of controlling a color, a temperature, andbrightness of the lighting device, as well as a wireless (remote)control technology employing cellular phones such as smartphones.

In addition thereto, communication functions may be added to the LEDlighting devices and display devices to thereby allow for the visiblelight wireless communication technology intended to simultaneouslyachieve essential purposes of an LED light source and purposes thereofas a communications means. This because LED light sources may beadvantageous, in that they have a relatively long lifespan as comparedto existing light sources and excellent power efficiency, allow for theimplementation of various colors of light, have a high switching speedfor digital communications, and enable digital controlling.

The visible light wireless communications technology may be a wirelesscommunications technology wirelessly transmitting information usinglight within the visible light wavelength band. The visible lightwireless communications technology may be differentiated from existingwired optical communications and infrared wireless communicationstechnologies in that it uses light within visible light wavelengthbands, and may be differentiated from wired optical communicationstechnology in terms of wireless communications environments thereof.

In addition, the visible light wireless communications technology mayhave convenience in that it is able to be freely used withoutregulations or permission in terms of the frequency of use thereof,unlike in radio frequency (RF) wireless communications, and may havediscrimination in that physical security is excellent and communicationlinks are able to be determined by a user's eyes. Furthermore, thevisible light wireless communications technology may havecharacteristics as a fused technology capable of simultaneouslyachieving essential purposes of a light source and communicationsfunctions thereof.

FIG. 24 is a cross-sectional view of a head lamp, illustrating anexample in which the semiconductor light emitting device according to anexemplary embodiment of the present inventive concept is applied to thehead lamp.

Referring to FIG. 24, a headlamp 9000 used as a vehicle lighting elementor the like may include alight source 9001, a reflective unit 9005 and alens cover unit 9004, the lens cover unit 9004 including a hollow guidepart 9003 and a lens 9002. The light source 9001 may be thesemiconductor light emitting device or the light emitting device packagedescribed according to the foregoing exemplary embodiments.

The headlamp 9000 may further include a heat radiating unit 9012dissipating heat generated by the light source 9001 outwardly. The heatradiating unit 9012 may include a heat sink 7010 and a cooling fan 9011in order to effectively dissipate heat.

In addition, the headlamp 9000 may further include a housing 9009allowing the heat radiating unit 9012 and the reflective unit 9005 to befixed thereto and supported thereby. One surface of the housing 9009 maybe provided with a central hole 9008 into which the heat radiating unit9012 is inserted to be coupled thereto.

The other surface of the housing 9009 integrally connected to and bentin a direction perpendicular to the one surface of the housing 9009 maybe provided with a forward hole 9007 such that the reflective unit 9005may be disposed above the light source 9001. Accordingly, a forward sidemay be opened by the reflective unit 9005 and the reflective unit 9005may be fixed to the housing 9009 such that the opened forward sidecorresponds to the forward hole 9007, whereby light reflected by thereflective unit 9005 disposed above the light source 9001 may passthrough the forward hole 9007 to thereby be emitted outwardly.

As set forth above, according to exemplary embodiments of the presentinventive concept, a hole-diffusion layer capable of dispersing holes ina transverse direction may be disposed on an electron-blocking layer,such that injection efficiency of the electrons may be improved andlight emission efficiency and light outputs may be improved.

While exemplary embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the spirit and scope ofthe present inventive concept as defined by the appended claims.

What is claimed is:
 1. A lighting system comprising: a lighting unitcomprising at least one lighting device; a sensing unit configured tomeasure at least one among atmospheric temperature and humidity; acontrolling unit configured to compare the at least one among thetemperature and the humidity measured by the sensing unit with setvalues and determine a color temperature of the lighting unit as aresult of the comparison; and a driving unit configured to drive to thelighting unit to have the determined color temperature, wherein the atleast one lighting device comprises at least one semiconductor lightemitting device including: a first conductivity type semiconductorlayer; an active layer disposed on the first conductivity typesemiconductor layer; an electron-blocking layer disposed on the activelayer; a second conductivity type semiconductor layer disposed on theelectron-blocking layer; and a hole-diffusion layer disposed between theelectron-blocking layer and the second conductivity type semiconductorlayer, wherein the hole-diffusion layer includes three layers havingdifferent energy band gaps and different resistance levels and at leastone of the three layers contains Al, a composition of the Al being lowerin the at least one layer than in the electron-blocking layer.
 2. Thelighting system of claim 1, wherein the at least one lighting devicecomprises a first lighting device configured to emit a first white lighthaving a first color temperature, and a second lighting deviceconfigured to emit a second white light having a second colortemperature.
 3. The lighting system of claim 2, wherein the first colortemperature is equal to or higher than 6000K and the second colortemperature is equal or lower than 4000K.
 4. The lighting system ofclaim 2, wherein the controlling unit is configured to control thedriving unit to drive the first lighting device and the second lightingdevice to generate white light having the determined color temperature.5. The lighting system of claim 1, wherein the three layers of thehole-diffusion layer include a first layer formed of In_(x1)Ga_(1−x1)N(0<x1<1), a second layer formed of GaN, and a third layer formed ofAl_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposed on theelectron-blocking layer.
 6. The lighting system of claim 5, wherein thehole-diffusion layer further includes an additional layer ofIn_(x3)Ga_(1−x3)N (0<x3<1) interposed between the second and thirdlayers.
 7. The lighting system of claim 1, wherein the three layers ofthe hole-diffusion layer include a first layer formed of GaN, a secondlayer formed of In_(x1)Ga_(1−x1)N (0<x1<1), and a third layer formed ofAl_(x2)Ga_(1−x2)N (0<x2<1), sequentially disposed on theelectron-blocking layer.
 8. The lighting system of claim 1, wherein thethree layers of the hole-diffusion layer include a first layer formed ofGaN, a second layer formed of A1 _(x2)Ga_(1−x2)N (0<x2<1), and a thirdlayer formed of In_(x1)Ga_(1−x1)N (0<x1<1), sequentially disposed on theelectron-blocking layer.
 9. The lighting system of claim 1, whereinthicknesses of the respective layers forming the hole-diffusion layerare within a range of 5 nm to 30 nm.